1997 Plymouth Voyager Parking / Running Lights - Dash Illumination Out

We are having a problem since 2006 with our Voyager on and off. Took it to the dealer to look at our parking / running lights not working and the dash not illuminating when the headlights are on. By the time we got it there, everything was working again. They didn't find anything. In 2007 we again had the problem, and they replaced a headlight switch. Again, the problem went away till this year, when it came back. They suggested replacing the switch, and since parts were hard to come by, we bought a used switch and had it installed. Worked 2 days and now we are back where we started. Headlights work, dash works and the odometer stays on bright - but the guages are not illuminated and the parking / running lights are not on which makes it very dangerous to drive at night. What else could it be? This is frustrating as heck.

Could be related to the body control module better known as the BCM. The BCM controls dash lighting via internal lamp driver circuits. It also plays a part in headlight and parking light functions amongst many other functions. Tough to prove without changing the BCM. Unfortunately that's a pricey $300+ box. You could try resetting the BCM by pulling the IOD fuse in the underhood fuse box for 2-3 minutes.

Why does changing the headlamp switch "fix" it. A theory. If a shop changes the switch by the book they have to disconnect the battery to disable the airbags. Should be done anytime anything behind the dash is accessed. When the battery is disconnected it cuts power to the BCM. The BCM is powered at all times. This loss of power resets the BCM.

Also thoroughly clean the battery terminals and the inside of the battery clamps themselves, get a good battery cleaning brush and clean the battery terminals and clamps until they are shiney. This era van is very susceptible to any kind of voltage fluctuations or poor grounds.

Sounds like your Body Control Module. If for some reason you lose power to it. It takes a while for it to reset I think there is some kind of surge protector or something in it that makes it slow to come back on. I pulled the battery on mine one time and it locked the power locks on me!! I found if you play with the power lock button it seems to tickle it into coming back on. Have you had trouble with the power locks when it's not working? You may need to get a new one too. You can check it here is the procedure! The Body Control Module (BCM), which receives input from various sensors, sends display information to instrument cluster and operates gauges. Instrument cluster incorporates a self-test diagnostic feature to identify electronic problems. BCM, Powertrain Control Module (PCM), and Transmission Control Module (TCM) are continuously monitored by the diagnostic system.

NOTE:Testing of instrument panel and gauges requires using a scan tool to check circuits connected to Body Control Module (BCM). See VEHICLE COMMUNICATIONS in BODY CONTROL COMPUTER article.

SELF-DIAGNOSTICS
With ignition off, press and hold TRIP and RESET buttons while turning ignition switch to ON position. Continue to hold TRIP and RESET buttons until odometer (http://www.2carpros.com/forum/1998-plymouth-voyager--help-vt216572.html#) window displays CODE (approximately 5 seconds). If problem exists, system will display diagnostic trouble codes. See DIAGNOSTIC CODE CHART table. If no problem exists, Code 999 (end test) will be displayed.
DIAGNOSTIC CODE CHART
CodeDescription
110.......Cluster Memory Fault
111.......Cluster Calibration Fault
905.......No CCD Bus Message From TCM
921.......Odometer Fault From BCM
940.......No CCD Bus Message From PCM

After diagnostic code display ends, instrument cluster will go into each of the following tests in order:
Dim test.
Calibration test.
Odometer segment test.
Electronic Transmission Range indicator segment test.
Dim Test
CHEC-0 will be displayed in odometer window. Instrument cluster will dim Vacuum Florescent (VF) display. If VF displays do not dim, a problem in instrument cluster exists. See BODY CONTROL COMPUTER TESTS in BODY CONTROL COMPUTER article.
Calibration Test
CHEC-1 will be displayed in odometer window. Each of instrument cluster gauges will move sequentially through each calibration point. See GAUGE CALIBRATIONS table. If gauge needle is not calibrated properly, a problem in instrument cluster exists. See BODY CONTROL COMPUTER TESTS in BODY CONTROL COMPUTER article for gauge recalibration procedures.
GAUGE CALIBRATIONS
Gauge Sequence.....Calibration Point
Speedometer
1......0 MPH (0 Km/h)
2......20 MPH (40 Km/h)
3......55 MPH (80 Km/h)
4......75 MPH (120 Km/h)
Tachometer
1.....0 RPM
2.....1000 RPM
3.....3000 RPM
4.....6000 RPM
Fuel Gauge
1.....Empty
2.....1/8 Full
3......1/4 Full
4.......Full
Temperature Gauge
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(http://www.2carpros.com/forum/1998-plymouth-voyager--help-vt216572.html#)
1......Cold
2......Low Normal
3......High Normal
4......Hot

Odometer Segment Test
CHEC-2 will be displayed in odometer window. Each segment of odometer will light sequentially. If any segment does not light, replace instrument cluster.
Electronic Transmission Range Indicator Segment Test
CHEC-3 will be displayed in odometer window. Each segment of electronic transmission range indicator will light sequentially. If any segment does not light, replace instrument cluster.
http://www.2carpros.com/forum/automotive_pictures/266999_bcm_1.jpg